• A recent genetic study has revealed that the adult male buried in the most elaborate recess of the Neolithic passage-tomb at Newgrange was the child of a first-degree incestuous union, suggesting that the complex was built as a burial monument for an endogamous family elite who may have been regarded as “god-kings.” The present paper shows how closely the bioarchaeological reality is paralled by the mythology of the site. Mythological narratives reveal the acceptance, prevalence and prestige of close consanguineous unions among the divine royalty of the Tuatha Dé Danann, the mythologically-nominated builders and users of Newgrange.